What is the fit between gears and shafts?

[LeJude]

The fitting form between gears fixed on shafts and the shafts varies depending on specific conditions. Factors such as the magnitude of power transmission, load stability, impact resistance, and assembly process must be considered. Generally, for small and stable loads, a clearance fit like H7/h6 is sufficient. For larger loads with impacts, transition fits such as H7/k6 or H7/m6 are used. These two are common fitting forms. Extension: In actual assembly, there are only two fitting forms—clearance and interference—which are easy to understand. Transition fits, however, can potentially be either clearance or interference fits; the exact fit is determined only after the parts are machined and assembled. Appropriate transition fits can be selected, such as those with a higher tendency toward clearance or interference fits.